1. Field of the Invention
The present invention relates to a touch control system and a sensing method thereof, and in particular to a touch control system and a sensing method thereof, that utilizes a turn-off signal as a trigger signal to monitor current variations.
2. The Prior Arts
In recent years, with the rapid progress of science and technology, various information devices are developed, produced, and put into use. In this respect, for the data input device, since volume of data processing is increasing rapidly, such that in case data is input only through a mouse or a keyboard, and output through a screen, for many applications, it tends to be rather slow. For this reason, the touch control panel has come into being. The touch control panel is able to give the feeling of a personalized input interface, that can be operated directly by users of any age brackets through touching menu items on a touch screen by means of a finger or a pen, to bring quite convenience to our daily life.
For the touch control panel technology at present, refer to FIG. 1 for a schematic diagram of a thin-film-transistor (TFT) matrix touch control system of the prior art. As shown in FIG. 1, the touch control system includes a touch control substrate 10 and a touch control circuit 12. On the touch control substrate 10 is provided with a plurality of sensing electrode units 14 arranged in an array, and a control electrode line group 16 and a detection electrode line group 18 crossing each other. Each sensing electrode unit 14 includes a TFT element 142, and a sensing electrode 144 connected to the TFT element 142. The control electrode line group 16 and the detection electrode line group 18 are connected respectively to the gate and source of the TFT element 142; and the sensing electrode units 14 is connected to the drain of the TFT element 142. The control electrode line group 16 controls the turn-on and turn-off of the TFT element 142. The detection electrode line group 18 is connected to the sensing electrode 144 through the TFT element 142.
The touch control circuit 12 includes: a control circuit 122, a signal detector circuit 124, and a driving source 126. The signal detector circuit 124 is connected electrically to the driving source 126 and the detection electrode line group 18. The control circuit 122 is connected electrically to the control electrode line group 16. The control circuit 122, in a scanning approach, outputs a turn-on signal column-by-column to each control electrode line of the control electrode line group 16, so that the TFT element 142 connected to the control electrode line having the turn-on signal is in a turn-on state, and the remaining TFT elements 142 are in a turn-off state. In this approach, the control circuits 122 controls column-by-column the TFT elements 142 on the control electrode line group 16 to be in a turn-on state. At this time, the detection electrode line group 18 acts in cooperation with the turn-on signal, inputs the touch control signal of the driving source 126 to the detection electrode line, so that the touch control signal thereon will flow through the TFT element 142, to the sensing electrode 144 connected to the control electrode line respectively. As such, along with the control circuit 122 outputs the turn-on signal column-by-column to the respective control electrode line, the signal detection circuit 124 detects column-by-column the variations of touch control signals on the sensing electrode unit 14 connected to the control electrode line. When a touch occurs, then the detection electrode line having its touch control signal variations greater than a threshold value can be found. Then, based on the control electrode line of the turned on TFT element 142, it can locate the sensing electrode unit 14 producing leakage current, thus finding the touch position.
The conventional circuit design mentioned above can only detect touch position, but it can not display. Therefore, an additional display substrate is required to use a gluing process to combine a touch control substrate with a display substrate into a touch control display. However, this kind of design increases its volume and circuit complexity, thus not being able to achieve compact size and thin profile. Moreover, when the variation of touch control signals on the detection electrode line is small, the touch position can not be detected accurately. Therefore, how to raise the detection sensitivity, and reduce its volume effectively, while reducing its cost, is a task that has to be accomplished urgently in this field.